Obsessive compulsive disorder (OCD), a syndrome characterized by obsessions and compulsions, has a lifetime prevalence of 1-2%. Accumulating evidence in support of the serotonergic hypothesis on the etiology of OCD led to several serotonin reuptake inhibitors (SSRIs) being approved as a treatment for this disorder. However, even with adequate dose and duration non-response or partial response is the role. In addition, side effects with the SSRIs prompt the search for better tolerated compounds (e.g., drop-out rates in the multi-center trials of fluoxetine, fluvoxamine, sertraline, and paroxetine were 23%, 24%, 27%, and 20% respectively. There has been considerable worldwide interest in St. John's Wort (SJW) (Hypericum perforatum) as a treatment from mild to moderate depression. To date, there have been 23 randomized trials suggests SJW is more effective than placebo for the treatment of outpatients with mild to moderate depression. SJW is very well tolerated with mild side effects observed in only 2.5% of cases in a large drug monitoring study. SJW's mechanism of action is postulated by be via inhibition of the synaptosomal uptake of serotonin, and thus there is a suggestion that SJW may be effective for OCD. A recent 12- week open-label trial with 123 subjects with a fixed dose of 450 mg of hypericin twice daily found a significant change from baseline to endpoint, with a mean Y-BOCS change of 7.4 points (p=.002). Five of the 12 subjects previously failed to respond to a trial with an SSRI. The current study will be a 12-week, double-blind, placebo controlled parallel group study. The purpose of the study is to examine the efficacy and safety of SJW compared to placebo. Fifty subjects will be randomly assigned to SJW (Alterra bran, 450 mg, 1.35 hypericin) or matching placebo. This will be a fixed-dose design at 450 mg bid. An intent-to- treat analysis will be employed Subjects will be evaluated weekly for two weeks than bi-weekly thereafter.